The present invention relates to an apparatus, for extracting silage from a cylindrical silo, of the kind including a suction extractor pipe having a suction aperture, and toothed wheels for feeding silage material to the suction aperture, and directly carrying the extractor device. The toothed wheels are freely and rotatably journalled on a plurality of supporting radial arms. Hereinafter such apparatus will be referred to as "of the kind described".
Known apparatus of the kind described (e.g. now described in German Offenlegungschrift No. 2532788, operable in such manner that the extractor device as a whole, comprising a driving system, lower and inner central frame element with cutting wheels or toothed drag wheels journalled on radial arms, is carried on the silage material in the cylindrical silo and is placed in slow rotation, the cutting wheels removing silage from the surface and by virtue of their agle of incidence feeding the same to the suction aperture of a central pneumatic and telescopic conveying pipe through which the silage is fed to a cowshed.
SInce the usual tall cylindrical silos for silage are erected in the open air, the case may arise in icy weather that the silage freezes, this freezing action occurring annularly inwards from the outside, i.e. first at the inner circumference of the silo. If the extractor device is in daily use, this frozen or frozen-on surface silage may be cut off by the conventional cutting wheels on the slowly revolving radial arms and fed to the suction aperture of the pneumatic suction extractor pipe. For reasons of safety, for prevention of damage to the generally enamelled inner casing surface of the silo, the periphery of the outermost cutting wheels situated at the extremities of the radial arms should always be set at a distance from the silo wall, so that a frozen residual layer then remains suspended on the inner silo surface in freezing weather. A layer of this kind may also adhere thereto if the silage happens to be very tacky. Until now, this layer had to be removed manually at frequent intervals, which was extremely onerous and time-consuming.
Consequently, it is an object of the invention to provide means for automatically breaking off and removing a tacky or frozen silage layer sticking to the inner surface of the silo during operation of the silage extracting apparatus.